Growing wood Truss Use in Japan: Wooden Elementary School Project

COFI Japan joint promotion efforts with the Japan Wood Truss Council is resulting in expanded opportunities for dimension lumber use in non-traditional markets. As a case in point, a new private elementary school is being constructed with wood in a town named “Tamamura” in Gunma prefecture: about a 100 km north of Tokyo. Currently the school’s East wing is under construction and is scheduled for completion in November 2019. Once finished, the school will have a total of 12 classrooms, a library, drawing and cooking room, main office, staff room and principal’s office for 200 children to attend grades one through six.

The building is a 2×4 structure that cleverly uses roof trusses to create the building’s unique open design and large spans. A special truss was also incorporated into the building’s roof design to allow a simple and clean installation of air-condition units within the ceiling. The general contractor for the project was Kadoya Kogyo and the sub-contractor for the 2×4 structure and trusses was R-Frame. R-Frame is an established 2×4 component manufacturer that recently started fabricating trusses and joined the Japan Wood Truss Council last fiscal year. To expand dimension wood use in non-residential applications, COFI Japan conducts extensive market outreach jointly with the JWTC in the form of joint seminars, web promotions and publications. This school project is an excellent example of Canadian SPF used in these truss applications. The owner and principal of the building commented that they went with wooden school building “as it proved to be the best way to provide a safe, healthy and natural environment for both students and staff in a cost-effective manner”.

MLIT Evaluation Body Certifies High Performance Midply

In recent years Canada Wood has been developing infill Midply shear wall systems to target increased market penetration of Canadian structural wood components in post and beam construction. We have recently attained an important milestone in certifying Hem-Fir (N) (Canada Tsuga) and OSB Midply infill walls for large scale and midrise rise post and beam applications. Based on shear wall test results obtained from in-fill type Midply with Canada Tsuga, we successfully obtained the voluntary evaluation certificate from Centre for Better Living (CBL) on July 26th or this year. The CBL is an MLIT*-designated performance evaluation body.  This certificate is an independent validation from expert judges that demonstrates how high performance Midply should be structurally designed in the large-scale post & beam wooden buildings.  It helps local building officials issue the building permits requiring the sophisticated engineering specifications.

Now that our high performance Midply shear wall for P&B has been approved by the evaluation body, we are preparing a structural design manual.  This is extremely important because the only structural design manual currently available for P&B is so-called HOWTEC’s “Gray Book” of which the scope is limited only to the shear wall factor 7.0 or less.  Our P&B Midply shear walls with Canada Tsuga performs as high as shear wall factor 10.0.  It is therefore important to develop a design manual alternative to the Gray Book to fully capture the benefits of this high-performance Midply shear wall system.

*MLIT: Ministry of Land, Infrastructure, Transport and Tourism

NLT Roof Structure Fire Tests Successful

As part of our current market access technical development projects, COFI and the Japan 2×4 Home Builders Association are aiming to obtain the ministerial approval of floor/roof diaphragms made from dimension based Nail-Laminated Timber (NLT). On July 16th and 17th, NLT structural roof assemblies were fire tested at the horizontal furnace in the Nishinihon Test Laboratory of Japan Testing Centre for Construction Materials (JTCCM) in Yamaguchi Prefecture. Subsequent to the floor assembly tests in December 2017, this test serves as preparation work to confirm the flame behavior before the real tests for obtaining the quasi-fire resistive ministerial approvals.

In the case of roof structures, the duration of burning is 30 minutes. On July 16th, the testing was conducted for the specimen with the same specifications as that for the approval. We applied vertical loads equivalent to 65 kg/m2 (live load required by the testing protocol) + 55 kg/m2 (equivalent to Japanese roofing tiles). On July 17th, three different types of NLT roof assemblies were tested, simulating fluted and curved NLTs. All test results demonstrated the sufficient quasi-fire resistive performance; i.e.) temperatures lower than 100 – 120 degree Celsius at the depth of 30 mm from the burned surface at the elapsed time of 30 minutes, no fire penetration through the cross section, deflection of less than 303 mm and less than 13.5 mm/minute of rate of deflection. Based on these successful test results, it is scheduled to conduct the real tests (performance evaluation tests) in November 2019 at the same laboratory. This work is intended to open up market opportunities for Canadian dimension lumber in Japanese mass timber applications.



Japan Housing & Non-Residential Starts Report for May 2019

Due in part to an unusually long Golden Week Holiday this year to market the commencement of the Reiwa imperial era, May total housing starts slumped 8.7% to 72,581 units. Rental housing continued to trail year prior results, falling 15.8%. Owner occupied, single family housing registered positive gains, rising 6.5%. While May marks the 8th consecutive monthly increase for owner-occupied housing, it is also the 9th consecutive monthly decline for rental housing.

Wooden housing fell 2.7% to 42,218 units. But given the relative strength in owner occupied homes, total floor area for wooden homes increased 2.1% to 4.21 million m2. Post and beam starts fell 3.1% to 33,020 units. Wooden pre-fab increased 14.8% to 984. Platform frame starts declined 3.0% to 8,214 units. By housing type, the breakdown in platform starts is as follows: custom ordered homes increased 5.3% to 2,699 units, rentals declined 5.9% to 4,342 units and built for sale spec homes fell 8.2% to 1,160 units.

May wooden non-residential starts totaled 1,524 buildings for a floor area of 277,564m2. Estimated wood use for the month was approximately 48,574m3. By number of overall buildings wood held a share of 36% and by floor area wood accounted for 8.6% of construction. The top wood end uses were elderly, medical and welfare facilities, mixed-use commercial/residential, restaurants & accommodation and business services.

Japan’s Third Largest 2×4 Elderly Care Building Completed

Exterior Photo of Nursing Home Tokiwagi Setagaya Nearing Completion

A uniquely designed mid-rise 2×4 nursing home commenced operation on July 1, 2019. It is centrally located in Tokyo’s Setagaya-ward and it will be the third large 2×4 elderly care project to be built in this city in the last three years that is 4-storeys or more. This is a pleasing trend and a hopeful sign that we will see more similar buildings go up here in the future.

The care facility is a 100-room senior multi-care complex that includes a daycare service program for seniors and a nursery to support the parents of young families living in the community. As we have seen with other midrise 2×4 buildings, a platform-frame and reinforced concrete hybrid structure were used in its construction. The basement and first floor of the building were constructed using reinforced concrete and the 2nd, 3rdand 4th floors with a 2×4 fireproof structure. The total floor area for the building is 4,989 m² and estimated SPF dimension lumber for the 2×4 structure covers an area of 720m³.

The facility is owned and managed by Social Welfare Corporation Tokiwakai and designed by MEDOX, an architect firm based in Tokyo that specializes in designing medical and social welfare facilities. The general contractor for the project was Mitsui Home. The owner and operator of this nursing home decided to build this facility with wood after visiting and touring the 5-storey 2×4/Midply, Seifu-kai elderly care project in Adachi, Tokyo a few years ago.